Google just started its drone delivery service in Australia, we are getting one step closer each month to for-fill an EVTOL future !

Did they consider ALL the emissions in the building and maintenance of a electric VTOL aircraft? How about its service life?

So how many VTOLs can you have before air traffic gets as bad as ground traffic?

The likelihood of charging with renewable energy such as solar increases as more such vehicles will be in private hands and residences are converted accordingly.

It's strange that ground vehicles are restrained by real world parameters but VTOL calculation get to take absolute best case scenarios as their functioning data. Who will be the owners of eVTOLs? Ride shares. Which means you have to add cost of getting to the client, finding a permitted landing spot. Waiting for clearance to take off. Flying to and from a recharging station much more often.

a couple of quick comments, an aircraft in flight uses very little energy, there is no rolling resistance for starters. A sailplane in flight only needs a little lift to keep it airborne for hours. add that to the direct flight approach, you don't need to follow existing ground routes. control wise, there are several things already in place. for conventional aircraft you fly in a height range depending upon your direction. This is designed to prevent aircraft flying into one another. with computer controlled flight systems you air taxi will not only communicate with a central control system but also with other air taxis in your area. also, if all of the air taxis fly at the same speed, then there will not be any conflicting traffic issues.

VTOL vehicles have practically everywhere for landing potential even on water with flotation. The traffic in 3D space is many times more capable of absorbing vehicles by orders or magnitude more than the much smaller area of narrow roadways. Air traffic can use many layers of controlled routes and or random 3D free flow with self flight computer coordination. When air traffic is uniformly distributed even with every car in the air at once it will still be thousands of feet separation vs bumper to bumper on roads.

@SimonClarke, there may be no rolling resistance, but there is a lot of aerodynamic drag at the speeds necessary to maintain lift. Sailplanes can stay aloft pretty well without power, but they're completely at the mercy of air currents, updrafts and winds. You can't really plan to go anywhere you want with them.

The study doesn't take into account the pollution created cleaning up the aircraft after each flight. Unless they can come up with software able to predict and counteract convective activity they're going to be flying vomitoriums. The airlines struggled for 20 years until they got an airplane that could fly above the weather. It was only then that people would readily fly. If the aircraft stays in the lower atmosphere it's going to be subjected to some pretty serious turbulence almost every day between the hours of 10 am to 6 pm. Now add weather and you're going to have days and times when the aircraft just can't fly. That doesn't happen to road vehicles except in very rare instances.

The evolution of a previous project by the University of Michigan, for the 'Urban Car Contest', that installed an OMC Wankel RCE, 45 HP, 530 cc per chamber, single rotor, air cooled housing, charge cooled rotor, double side and peripheral intake port, seems inspired the German 'Smart'. So, we can expect continuation of the Michigan idea about VTOL taxi. Good news!